It is already known to place light-emitting devices at various locations of a motor vehicle to reveal the outline of the vehicle.
Such light-emitting devices are generally light-emitting diodes (LEDs) grouped together and enclosed in transparent housings, which are added to or incorporated in external members or which are stuck behind cabin windows.
Those devices perform their function and improve traffic safety by making the vehicle more visible at night. Nevertheless, they require means that are expensive both for manufacture and for assembly on the vehicle. They also constitute devices that can break down, and consequently they increase the cost of maintaining the vehicle.
Another drawback of such known devices is their relative fragility, which means they cannot be placed just anywhere on a vehicle.
Furthermore, they provide light-emitting surfaces that are small and limited by the number of LEDs, which constitutes a limitation both in terms of the effectiveness of the signaling provided and in terms of the decorative possibilities they offer.
In an attempt to remedy those drawbacks, proposals have been made in the prior art, and in particular in EP 1 022 187, for a signaling device, and more precisely a flashing direction-indicator device arranged on a rearview mirror, in which a portion of the casing of the mirror is constituted by a translucent part serving as a light guide. Thus, light rays coming from point light sources disposed exactly in register with the thickness of the part are diffused via the outside face of the part towards the front and the side of the vehicle. Fine ribs are formed on the inside face of the translucent part to reflect the light rays in the horizontal direction, and in particular to prevent them from being diffused downwards.
In such a device, a problem consists in that the translucent part must be capable of withstanding impacts and must also be sufficiently thick to be effective in collecting the light rays emitted by the point light sources, which requires a large amount of material, giving rise to significant weight, bulk, and cost.